Building a library around axum

help
1

For my CMS/Webapp framework project I'm using axum to handle the requests and responses. I have a App struct to contain the application state and some logic and a Plugin trait:

struct MyPlugin;

impl Plugin for MyPlugin {
	fn initialize(&self, app: App) {
		// do things like add routes
	}
}

// register it to be run on startup
app.register_plugin(MyPlugin);

With this there are two main problems I need to solve:

  • There are two approaches to state: using Router.with_state and Extension. Is using Extension the better method?
  • Allowing use of the Router: its methods being self-consuming is tricky, would it be best to provide methods in App and then build it after plugins are run?
3

State is used for global state shared across requests, whereas extensions contain request-local data, like data retrieved from an access token, for example.

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5

Is it correct that only one type of state can be held? In that case should I provide a typemap-like API for state from end applications?

6

This is a really unhelpful response—I asked specifically about axum since it fits the needs of my project. I fail to see how the code you provided could possibly be integrated into the project, and I suspect it came from an LLM. You also called me 'he', which considering I am nonbinary, is incorrect.

3 Likes
7

Multiple State objects is tricky but possible, as long as you can split your routes and state in a way that each route only needs one State extractor. I'm not sure how you envision your API, but alternatively Axum also allows extracting "substate", if the substate type implements FromRef<State>. So if you can't split routes and state in a way that satisfies S in Router<S>, maybe you could make the substate-approach work instead. If that doesn't work or leads to an inelegant API, inserting the different states as a Extensions instead of using State would be the better option after all, in my opinion.

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9

As far as I can tell the substate method wouldn't be extensible so I'll go with Extensions. I am thinking maybe I should have an API for registering Routers similar to the one for Plugins, then having code in App to merge them. Does this seem like a good approach?

10

Axum documentation about State has a small section that suggests how to implement state extraction in libraries. See State in axum::extract - Rust.

3 Likes